伊舒地堑下第三系沉积体系特征及其油气勘探意义

辫状河三角洲体系和湖底扇体系,构成了伊舒地堑下第三系最主要的粗粒碎屑沉积体系。它们以短轴方向搬运一沉积为主。盆地不对称双断导致沉降和沉积中心偏向于主断裂一侧,而辫状河三角洲体系则在缓坡一侧发育。辫状河三角洲体系作为地堑中的重要储集岩、它的发育与横向构造,如横向断层、断价、边坡以及基底凸起等构造单元有密切关系,因此,它们是油气勘探的重要靶区。

PROPERTIES OF EOGENE SEDIMENTARY SYSTEM IN YISHU GRABEN AND ITS HYDROCARBON SIGNIFICANCE

Braided delta system and sublacustrine fan system constitute the primary Eogene coarse elastic sediments which are characterized mainly by short axial direction transportation depositlon.The asymmetrical bilateral fractures whthin the graben resulted in the drift of subsidence center and depocfnter towards the main fracture;the braided delta system then developed on the gentle slope.As the main reservoirs in the graben,the development of the braided delta system was closely related to its transverse structtyres such as cross faults,fault benches, borderland slopes and basement uplifts.Thus these structures should be im portant targets for oil and gas exploration.